Persons seeking to sponsor their spouse to Canada may be ineligible to do so if they:
1) violated the terms of a sponsorship agreement in the past;
2) are in arrears of their spousal support or child support payments;
3) received governmental financial help, except for disability;
4) were convicted of sexual or violent crimes;
5) were sponsored as a spouse in the past and became a PR less than five years ago;
6) defaulted on, made late payments on or missed payments for immigration loan;
7) are in prison; or,
8) have declared bankruptcy and have not been released from it.
http://www.cic.gc.ca/english/index.asp